* dev: add GitHub detailed issue templates
* dev: update PR template
contributing guidelines link is already in PR UI
changelog message is no longer needed -- it is generated from commit messages
* dev: use bug report template on CMS crash
* Update bug_report.md
Inspired by Docker and Yarn. We can add more things later if we need
them, but I think this is a good start.
Signed-off-by: David Calavera <david.calavera@gmail.com>